[R-390] DIY cabinet/shielding questions

[Barry Hauser]

Hi Adam & gang:

First of all -- welcome aboard!

When putting an R-390A in a cabinet or rack, an important consideration is
ventilation.  You don't want to suffocate the radio.

The basic mil procedure when installing in a cabinet or rack was to remove
top and bottom covers, which is why so many are missing.  It pays to keep
the Utah cover in place as there aren't many tubes under it and it helps
keep dust out of the coils.

Might be arguable, but the 390's are pretty well shielded while uncontained.
Additional shielding is needed only in special situations.  Wood has
insulating properties, so you have to make sure there are plenty of vents in
whatever  you build.  The '390's have the "H-frame" design with modules
suspended on the bottom.  The convection air flow is primarily from the
bottom and out the side panel holes (for the "downstairs modules").  So, the
case design should have openings on the bottom AND the sides, not just one
or the other.

Consider simply getting a nice top cover.  If Fair Radio won't break a set,
check with Hank Arney.

If you're going to make a full wooden cabinet, plan on cutting a lot of vent
holes.  (Some kind of open frame design might be more practical.) Leave the
top and bottom covers off.  If you add screening, I'd suggest a fine mesh so
it helps keep some dust out, but not so fine that it restricts airflow.

You might be able to find a standard cabinet at a reasonable price (under
$100) that will fit -- or maybe one that's taller with room for
"accessorizing".

Barry



Adam wrote:
> Hello everyone. I recently began work on my R-390A and, since I don't have
> any sort of cabinet or rack for the set to go in, I've been toying with
the idea
> of building a wooden cabinet for it. I thought that this sort of project
> would be relatively straightforward, but then the issue of shielding came
to mind.
> Are the top and/or bottom covers detrimental to the correct operation of
the
> receiver? I have the bottom cover and the oft-mentioned "Utah plate," but
am
> currently missing the top cover (anyone know of a source for just this one
> cover? Would Fair Radio be willing to sell me only the top one, since the
bottom
> one is passable?). While looking through the overheating section of the
R-390A
> Pearls of Wisdom archive, I found one post which said that the milspec
metal
> cabinet one owner had used RFI screening over all the holes in the case.
Would
> it be better to try to restore the top cover, cover the insides of the
wooden
> case with some sort of metal screening, both, or would neither be
necessary?
> Also, what would be the best way to bolt the R-390A into the wooden
cabinet?
> TIA.
> -Adam
>
> Adam Vaughn
> Collector of old computers, video game systems, radios and other
electronic
> equipment...
> Visit my page at
> http://www.angelfire.com/ma2/AdamVon/index.html
>
>
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